Longer-term open-label study of adjunctive riluzole in treatment-resistant depression

Treatment of Depression in Huntington's Disease: A Systematic Review

Depression is a common psychiatric disorder among individuals with Huntington's disease (HD). Depression in HD and major depressive disorder appear to have different pathophysiological mechanisms. Despite the unique pathophysiology, the treatment of depression in HD is based on data from the treatment of major depressive disorder in the general population. The objective of this systematic review was to conduct a comprehensive evaluation of the available evidence. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Studies on the treatment of depression in HD were identified by searching MEDLINE, Embase, and PsycInfo. The initial search yielded 2,771 records, 41 of which were ultimately included. There were 19 case reports, seven case series, three cross-sectional studies, one qualitative study, nine nonrandomized studies, and two randomized trials among the included studies. The most common assessment tools were the Hospital Anxiety and Depression Scale (N=8), the Beck Depression Inventory (N=6), and the Hamilton Depression Rating Scale (N=6). Only 59% of the included studies assessed depressive symptoms with a scoring system. The pharmacological options for the treatment of depression included antidepressants and antipsychotics. Nonpharmacological approaches were multidisciplinary rehabilitation, psychotherapy, and neurostimulation. Limited evidence on the treatment of depression in HD was available, and this literature consisted mainly of case reports and case series. This systematic review highlights the knowledge gap and the pressing need for HD-specific research to determine the efficacy of treatment approaches for depression in HD.

Real-world safety profile of riluzole: a systematic analysis of data from the FAERS database and case reports

BACKGROUND

The study aims to obtain the safety profile of riluzole in the real world and provide reference for clinical drug applications.

RESEARCH DESIGN AND METHODS

Proportional reporting ratio (PRR) was used to detect riluzole adverse drug reactions (ADRs) from the data between the first quarter of 2004 and the third quarter of 2022 in the FDA adverse event reporting system database (FAERS). Case reports of riluzole published in PubMed, Embase, and Web of Science before November 2022 were reviewed, and patient's data were extracted.

RESULTS

FAERS analysis identified 86 ADRs. Gastrointestinal system disorders and respiratory, thoracic, and mediastinal disorders account for 12 of the top 20 most frequent ADRs. Similarly, 9 of the 20 highest PRR ADRs were gastrointestinal system disorders and respiratory, thoracic, and mediastinal disorders. Twenty-two published riluzole-associated cases were identified in the literature. Respiratory, thoracic, and mediastinal disorders were the most commonly reported cases (n = 9), followed by gastrointestinal disorders, pancreatitis (n = 5).

CONCLUSIONS

Strong ADRs between riluzole and pancreatitis were identified, which reminds clinicians to monitor patients carefully. For patients with respiratory symptoms, clinicians should pay attention to distinguish the cause of their occurrence, and take appropriate measures. Beware that riluzole may increase the risk of inflammatory reactions and inappropriate vasopressin secretion and hyponatremia due to respiratory failure.

Prophylactic Efficacy of Riluzole against Anxiety- and Depressive-Like Behaviors in Two Rodent Stress Models

Introduction

Chronic stress-related illnesses such as major depressive disorder and post-traumatic stress disorder share symptomatology, including anxiety, anhedonia, and helplessness. Across disorders, neurotoxic dysregulated glutamate (Glu) signaling may underlie symptom emergence. Current first-line antidepressant drugs, which do not directly target Glu signaling, fail to provide adequate benefit for many patients and are associated with high relapse rates. Riluzole modulates glutamatergic neurotransmission by increasing metabolic cycling and modulating signal transduction. Clinical studies exploring riluzole's efficacy in stress-related disorders have provided varied results. However, the utility of riluzole for treating specific symptom dimensions or as a prophylactic treatment has not been comprehensively assessed.

Methods

We investigated whether chronic prophylactic riluzole (∼12-15 mg/kg/day p.o.) could prevent the emergence of behavioral deficits induced by unpredictable chronic mild stress (UCMS) in mice. We assessed (i) anxiety-like behavior using the elevated-plus maze, open-field test, and novelty-suppressed feeding, (ii) mixed anxiety/anhedonia-like behavior in the novelty-induced hypophagia test, and (iii) anhedonia-like behavior using the sucrose consumption test. Z-scoring summarized changes across tests measuring similar dimensions. In a separate learned helplessness (LH) cohort, we investigated whether chronic prophylactic riluzole treatment could block the development of helplessness-like behavior.

Results

UCMS induced an elevation in anhedonia-like behavior and overall behavioral emotionality that was blocked by prophylactic riluzole. In the LH cohort, prophylactic riluzole blocked the development of helplessness-like behavior.

Discussion/Conclusion

This study supports the utility of riluzole as a prophylactic medication for preventing anhedonia and helplessness symptoms associated with stress-related disorders.

Is depression the missing link between inflammatory mediators and cancer?

Patients with cancer are at greater risk of developing depression in comparison to the general population and this is associated with serious adverse effects, such as poorer quality of life, worse prognosis and higher mortality. Although the relationship between depression and cancer is now well established, a common underlying pathophysiological mechanism between the two conditions is yet to be elucidated. Existing theories of depression, based on monoamine neurotransmitter system dysfunction, are insufficient as explanations of the disorder. Recent advances have implicated neuroinflammatory mechanisms in the etiology of depression and it has been demonstrated that inflammation at a peripheral level may be mirrored centrally in astrocytes and microglia serving to promote chronic levels of inflammation in the brain. Three major routes to depression in cancer in which proinflammatory mediators are implicated, seem likely. Activation of the kynurenine pathway involving cytokines, increases tryptophan catabolism, resulting in diminished levels of serotonin which is widely acknowledged as being the hallmark of depression. It also results in neurotoxic effects on brain regions thought to be involved in the evolution of major depression. Proinflammatory mediators also play a crucial role in impairing regulatory glucocorticoid mediated feedback of the hypothalamic-pituitary-adrenal axis, which is activated by stress and considered to be involved in both depression and cancer. The third route is via the glutamatergic pathway, whereby glutamate excitotoxicity may lead to depression associated with cancer. A better understanding of the mechanisms underlying these dysregulated and other newly emerging pathways may provide a rationale for therapeutic targeting, serving to improve the care of cancer patients.

Pharmacological targeting of cognitive impairment in depression: recent developments and challenges in human clinical research

Impaired cognition is often overlooked in the clinical management of depression, despite its association with poor psychosocial functioning and reduced clinical engagement. There is an outstanding need for new treatments to address this unmet clinical need, highlighted by our consultations with individuals with lived experience of depression. Here we consider the evidence to support different pharmacological approaches for the treatment of impaired cognition in individuals with depression, including treatments that influence primary neurotransmission directly as well as novel targets such as neurosteroid modulation. We also consider potential methodological challenges in establishing a strong evidence base in this area, including the need to disentangle direct effects of treatment on cognition from more generalised symptomatic improvement and the identification of sensitive, reliable and objective measures of cognition.

The stressed synapse 2.0: pathophysiological mechanisms in stress-related neuropsychiatric disorders

Stress is a primary risk factor for several neuropsychiatric disorders. Evidence from preclinical models and clinical studies of depression have revealed an array of structural and functional maladaptive changes, whereby adverse environmental factors shape the brain. These changes, observed from the molecular and transcriptional levels through to large-scale brain networks, to the behaviours reveal a complex matrix of interrelated pathophysiological processes that differ between sexes, providing insight into the potential underpinnings of the sex bias of neuropsychiatric disorders. Although many preclinical studies use chronic stress protocols, long-term changes are also induced by acute exposure to traumatic stress, opening a path to identify determinants of resilient versus susceptible responses to both acute and chronic stress. Epigenetic regulation of gene expression has emerged as a key player underlying the persistent impact of stress on the brain. Indeed, histone modification, DNA methylation and microRNAs are closely involved in many aspects of the stress response and reveal the glutamate system as a key player. The success of ketamine has stimulated a whole line of research and development on drugs directly or indirectly targeting glutamate function. However, the challenge of translating the emerging understanding of stress pathophysiology into effective clinical treatments remains a major challenge.

High-fat diet induces depression-like phenotype via astrocyte-mediated hyperactivation of ventral hippocampal glutamatergic afferents to the nucleus accumbens

Comorbidity exists between metabolic disorders and depressive syndrome with unclear mechanisms. To characterize the causal relationship, we adopted a 12-week high-fat diet (HFD) to induce metabolic disorder and depressive phenotypes in mice. Initially, we identified an enhanced glutamatergic input in the nucleus accumbens of HFD mice. Retrograde tracing and chemogenetic inhibition showed that the hyperactive ventral hippocampal glutamatergic afferents to the nucleus accumbens determined the exhibition of depression-like behavior in HFD mice. Using lentiviral knockdown and overexpression approaches, we proved that HFD-induced downregulation of glial glutamate transporters, GLAST and GLT-1, contributed to the observed circuit maladaptations and subsequent depression-like behaviors. Finally, we identified a potential therapeutic agent, riluzole, which could mitigate the HFD-induced behavioral deficits by normalizing the expressions of GLAST and GLT-1 and ventral hippocampal glutamatergic afferents to the nucleus accumbens. Overall, astrocyte-mediated disturbance in glutamatergic transmission underlies the metabolic disorder-related depressive syndrome and represents a therapeutic target for this subtype of depressive mood disorders.

Astrocytes in Bipolar Disorder

Bipolar disorder (BD) is a complex group of neuropsychiatric disorders, typically comprising both manic and depressive episodes. The underlying neuropathology of BD is not established, but a consistent feature is progressive thinning of cortical grey matter (GM) and white matter (WM) in specific pathways, due to loss of subpopulations of neurons and astrocytes, with accompanying disturbance of connectivity. Dysregulation of astrocyte homeostatic functions are implicated in BD, notably regulation of glutamate, calcium signalling, circadian rhythms and metabolism. Furthermore, the beneficial therapeutic effects of the frontline treatments for BD are due at least in part to their positive actions on astrocytes, notably lithium, valproic acid (VPA) and carbamazepine (CBZ), as well as antidepressants and antipsychotics that are used in the management of this disorder. Treatments for BD are ineffective in a large proportion of cases, and astrocytes represent new therapeutic targets that can also serve as biomarkers of illness progression and treatment responsiveness in BD.

Bi-ancestral depression GWAS in the Million Veteran Program and meta-analysis in >1.2 million individuals highlight new therapeutic directions

Major depressive disorder is the most common neuropsychiatric disorder, affecting 11% of veterans. Here we report results of a large meta-analysis of depression using data from the Million Veteran Program, 23andMe, UK Biobank and FinnGen, including individuals of European ancestry (n = 1,154,267; 340,591 cases) and African ancestry (n = 59,600; 25,843 cases). Transcriptome-wide association study analyses revealed significant associations with expression of NEGR1 in the hypothalamus and DRD2 in the nucleus accumbens, among others. We fine-mapped 178 genomic risk loci, and we identified likely pathogenicity in these variants and overlapping gene expression for 17 genes from our transcriptome-wide association study, including TRAF3. Finally, we were able to show substantial replications of our findings in a large independent cohort (n = 1,342,778) provided by 23andMe. This study sheds light on the genetic architecture of depression and provides new insight into the interrelatedness of complex psychiatric traits.

Experimental Therapeutics in Treatment-Resistant Major Depressive Disorder

Treatment-Resistant Depression (TRD) patients remain a challenging sub-division of patients with Major Depressive Disorder (MDD) in day to day clinical practice. As with any diagnostic condition, comprehensive evaluation, exclusion of other psychiatric conditions, assessment of co-morbid medical and psychiatric illnesses and psychosocial stressors are the keys to appropriate diagnosis and subsequent management. There are various management options available for the treatment of MDD, however, about 30% of the patients fail to achieve full remission of symptoms despite multiple trials and belong to this sub-category of MDD. This article brings forth discussion of other non-conventional medication and non-medication treatment alternatives that merit exploration of their efficacy in TRD. Many of the proposed novel medications and other treatment modalities such as Deep Brain Stimulation, exercise, yoga are already used for other medical and psychiatric disorders and have some evidence suggesting their potential benefits in TRD in conjunction with conventional medications or even as monotherapy. Nevertheless, more research is needed in this direction to establish effectiveness.

Harmonizing the Neurobiology and Treatment of Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a common, chronic, and oftentimes disabling disorder. The only established first-line treatments for OCD are exposure and response prevention, and serotonin reuptake inhibitor medications (SRIs). However, a subset of patients fails to respond to either modality, and few experience complete remission. Beyond SRI monotherapy, antipsychotic augmentation is the only medication approach for OCD with substantial empirical support. Our incomplete understanding of the neurobiology of OCD has hampered efforts to develop new treatments or enhance extant interventions. This review focuses on several promising areas of research that may help elucidate the pathophysiology of OCD and advance treatment. Multiple studies support a significant genetic contribution to OCD, but pinpointing the specific genetic determinants requires additional investigation. The preferential efficacy of SRIs in OCD has neither led to discovery of serotonergic abnormalities in OCD nor to development of new serotonergic medications for OCD. Several lines of preclinical and clinical evidence suggest dysfunction of the glutamatergic system in OCD, prompting testing of several promising glutamate modulating agents. Functional imaging studies in OCD show consistent evidence for increased activity in brain regions that form a cortico-striato-thalamo-cortical (CSTC) loop. Neuromodulation treatments with either noninvasive devices (e.g., transcranial magnetic stimulation) or invasive procedures (e.g., deep brain stimulation) provide further support for the CSTC model of OCD. A common substrate for various interventions (whether drug, behavioral, or device) may be modulation (at different nodes or connections) of the CSTC circuit that mediates the symptoms of OCD.

Safety and efficacy of riluzole in patients undergoing decompressive surgery for degenerative cervical myelopathy (CSM-Protect): a multicentre, double-blind, placebo-controlled, randomised, phase 3 trial

BACKGROUND

Degenerative cervical myelopathy represents the most common form of non-traumatic spinal cord injury. This trial investigated whether riluzole enhances outcomes in patients undergoing decompression surgery for degenerative cervical myelopathy.

METHODS

This multicentre, double-blind, placebo-controlled, randomised, phase 3 trial was done at 16 university-affiliated centres in Canada and the USA. Patients with moderate-to-severe degenerative cervical myelopathy aged 18-80 years, who had a modified Japanese Orthopaedic Association (mJOA) score of 8-14, were eligible. Patients were randomly assigned (1:1) to receive either oral riluzole (50 mg twice a day for 14 days before surgery and then for 28 days after surgery) or placebo. Randomisation was done using permuted blocks stratified by study site. Patients, physicians, and outcome assessors remained masked to treatment group allocation. The primary endpoint was change in mJOA score from baseline to 6 months in the intention-to-treat (ITT) population, defined as all individuals who underwent randomisation and surgical decompression. Adverse events were analysed in the modified intention-to-treat (mITT) population, defined as all patients who underwent randomisation, including those who did not ultimately undergo surgical decompression. This study is registered with ClinicalTrials.gov, NCT01257828.

FINDINGS

From Jan 31, 2012, to May 16, 2017, 408 patients were screened. Of those screened, 300 were eligible (mITT population); 290 patients underwent decompression surgery (ITT population) and received either riluzole (n=141) or placebo (n=149). There was no difference between the riluzole and placebo groups in the primary endpoint of change in mJOA score at 6-month follow-up: 2·45 points (95% CI 2·08 to 2·82 points) versus 2·83 points (2·47 to 3·19), difference -0·38 points (-0·90 to 0·13; p=0·14). The most common adverse events were neck or arm or shoulder pain, arm paraesthesia, dysphagia, and worsening of myelopathy. There were 43 serious adverse events in 33 (22%) of 147 patients in the riluzole group and 34 serious adverse events in 29 (19%) of 153 patients in the placebo group. The most frequent severe adverse events were osteoarthrosis of non-spinal joints, worsening of myelopathy, and wound complications.

INTERPRETATION

In this trial, adjuvant treatment for 6 weeks perioperatively with riluzole did not improve functional recovery beyond decompressive surgery in patients with moderate-to-severe degenerative cervical myelopathy. Whether riluzole has other benefits in this patient population merits further study.

FUNDING

AOSpine North America.